Expression of recombinant HAO3 from an Iranian isolate of Hyalomma anatolicum anatolicum in Pichia pastoris and evaluation of its antigenicity

Hyalomma anatolicum anatolicum tick is considered as one of the main problem of ruminants’ productivity in endemic countries such as parts of Africa, the Middle East and India. The disease is economically important and hence, its control and eradication is a priority. This problem reinforces the need for alternative approach like vaccine to control tick infestations instead of continuous application of acaricide which led to the natural selection of the acaricide-resistant ticks. Therefore, the present study provided evidence for the construction of transformant containing the chromosomally integrated multi-copy expression cassettes of HAO3, its successful and efficient expression in Pichia pastoris yeast and purification of the secreted protein by ultrafiltration (UF) system in a high level yield and purity.The result of antigenicity assay for the rHAO3 protein pointed well toward its capability for the elicitation of antibody response in immunized rabbits. Interestingly, the results indicated that the expressed HAO3 protein reacted well with mid gut antigen (MGAg) and rBm86 (Gavac) antisera in ELISA and western blot assays making it evident that the epitopes present in expressed protein are well recognized by the antibodies against MGAg and rBm86 proteins. Moreover, the presence of cross-reactive epitopes between rHAO3 protein with its native antigen from mid gut cells was also determined.